Ultimate Guide to Loft Conversions

If you are thinking of a loft or attic conversion to create a new usable space, this guide will help you determine if your loft is suitable, if you are allowed to convert it (loft conversion building regulations), what the different base options are, loft conversion costs & budgets and who you will need to do the work for you.

Whilst this guide will help you with initial appraisal steps, we would normally recommend seeking advice from an architect to take it to the next step of developing your ideas into a feasible set of drawings. After discussing with an architect and using this guide to build an outline of your project, please feel free to contact us for a free quote if would like us to conduct a structural inspection and design the new structural elements.

Loft conversion plans: can I convert my loft?

Limited headroom in a typical domestic roof space, unfortunately, makes most lofts unsuitable for conversion.

So how can you tell if yours would be suitable? Although loft conversion regulations, (UK Building Regulations) have dropped the requirement for minimum headroom in a habitable room, for practical purposes the final headroom for attic conversions should not be less than 2.1m.

However, it’s not just a case of measuring from your existing loft floor up to the highest point. During conversion, the floor joists, (which are normally no more than 100mm deep), often need be increased to 150mm or more, and where headroom is limited, dormers will be required to allow movement around the room without having to stoop.

Next, have a look at the type of roof construction you have.

Many roofs have trussed rafters. These are prefabricated before delivery to site and have spiked-plate connectors like the one in the drawing. If you have this type of structure, your loft, unfortunately, won’t be suitable for conversion as the trusses are designed to very tight tolerances and the removal of any of the internal timbers will destroy the integrity of the whole truss, and therefore, the roof. It is not impossible to convert such roofs but it will cost much more to do so, and may make your conversion financially impractical. Speak to your architect if this applies to your roof so they can tell you which options you have and how much it would cost to convert the structure of the roof.

Aside from these factors, most other structural obstacles can be overcome.

Could I add space to my loft?

There are many types of loft conversion. Where possible, most people who do attic conversions add space either by joining together adjacent loft spaces to create one larger loft space, installing one or more dormer windows, (windows that stick out of your roof to increase head space) or creating a wide / full-width dormer, (meaning one whole side of your pitched roof is converted into a flat roof with windows all along the vertical face).

Please note, even if you decide only to opt for Velux-style windows, which don’t protrude from your roof at all, you may still need permission (e.g. if you live in a conservation area).

Others may wish to consider adding outside space to their loft in the form of a cut-in balcony. This type of attic conversion can add a lot of natural light whilst affording nice views.

Victorian terrace loft conversions

If you live in a traditional Victorian terrace house with a downstairs kitchen and upstairs bathroom extending out the back of your house into your back yard or garden, a very common type of conversion is the L-Shaped loft extension.

This allows you to convert the loft in the main part of the house using a wide dormer, and then the extension goes round the corner into another wide dormer over the upstairs bathroom.

Since a lot of Victorian terraces are difficult to convert further than the common rear kitchen extension, (bathroom above), the L-shaped loft conversion in this type of property is very common and results in a new 2nd or 3rd floor to the building which matches (or is very close to) the floor space of the floors below.

Do I need an architect for my loft conversion?

For all types of loft conversions, technically, you can do everything yourself from designing and drawing up the loft conversion plans to doing the building yourself, but the requirements are wide and can be complex, so you are highly advised to employ the services of an architect who can keep you in line with all of your obligations and safety considerations, not just provide creative ideas and flair.

Furthermore, you should ask your architect whether or not they can act on your behalf with any party wall disputes, because if there are any party walls involved, you might otherwise need a specialist surveyor, which will cost you extra money.

What structural changes are needed for attic conversions?

Whilst this question can only be answered by a qualified Structural Engineer, to give you the answer for your specific loft, the following structural changes are common examples found in loft conversion plans. The number of “£” signs denotes the relative cost of the alteration. Some points aren’t strictly structural, but they are often done at the same time as the structural changes.

CAN'T I JUST BOARD MY LOFT AND USE IT FOR STORAGE?

Some people board-out their loft floor, fit one or two Velux windows, install a staircase and say that they are just using the roof space for storage without applying for any permissions. However, this type of basic conversion would actually be classed as a “habitable room” and be subject to all the loft conversion regulations we discussed above. It would therefore not be a lawful conversion and aside from breaking the law, you may not be able to sell your house in the future, (the buyer will ask for proof of the local council’s approval).

If there is no fixed staircase but just a loft ladder, this is regarded as a borderline case but if a Building Inspector sees that the loft is being used for anything other than storage, a retrospective application will have to be made.

Budgeting for loft conversions

A very simple loft conversion could cost £10,000 to £15,000. This assumes you want a new staircase, new windows, proper flooring and insulated walls / ceilings.

If you would like new dormer windows instead of Velux-style windows, this type of conversion could cost in the region of £20,000 to £30,000.

If you want to include a bathroom, with water supply, waste plumbing, ventilation, fit-out etc., this type of loft conversion could cost between £35,000 and £50,000.

However, in order to estimate the budget for your project specifically, we have put together the following Loft Conversion Budget Planner showing all the typical component loft conversion costs. Please note that these values are given as very rough estimate ranges only, and you should expect that your quoted values may extend below or above the limits that we have indicated. That said, we hope you find it useful. You are welcome to save, share or print this out and use it as a checklist.

Loft Conversion Budget Planner

Responsibilities during building work

If you are not hiring an architect, and you are managing the process yourself, you may have responsibility for overall safety on-site and you may need to create a Health & Safety plan and ensure the plan is adhered to at all times. But don’t feel daunted by this: you don’t need specialist expertise as it is mostly just common sense. Plus, there are plenty of guides online to help you.

There is a handy form at this link to help your builder plan the work and address any safety issues and furthermore, if you search online for “CDM for Self Builders and Renovators”, you will find plenty more guidance.

Funding a loft conversion

Whilst many people will look to fund attic/loft conversions with credit or savings, it may be worth considering the use of future capital appreciation as a way of funding your project.

Given that most types of loft conversion generally increase the value of a house, (by up to 20% in many cases), there are some lenders who now offer finance before you start work, based on the future increased value of your property. Therefore, if the lender can be convinced that your property will increase in value by a certain amount, they could lend you a percentage of that amount before work commences to cover your loft conversion costs.

Depending on the lender, this could potentially be done as a “Further Advance” to your existing mortgage. Ask a specialist finance or mortgage broker about home development finance.